421689 ÷ 15 
We want to divide 421689 by 15.

Step 1:
15 goes into 4 0 times with a remainder of 4.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 4 leaves us with 4.
Include the next digit (2) from the dividend after 4, then repeat: 42 / 15

Step 2:
If we divide 42 by 15, we get 2 and a remainder of 12.
Write down 2 as next digit of the result. 
Result so far: 2.0
If we take 30 away from 42, we end up with 12.
Append the next digit (1) from the dividend to 12 and continue with: 121 / 15

Let's proceed to step 3:
When dividing 121 by 15, we get 8 with a remainder of 1.
Put 8 as the next digit of the answer. 
Result so far: 28.0
Deduct 120 from 121 and we're left with 1.
Take the next digit (6) from the dividend and append it to 1, then repeat: 16 / 15

Step 4:
The number 15 fits into 16 1 times, leaving a remainder of 1.
Record the quotient 1 as the next digit in the result. 
Result so far: 281.0
Deduct 15 from 16 and we're left with 1.
Include the next digit (8) from the dividend after 1, then repeat: 18 / 15

On to step 5:
18 divided by 15 is 1 with a remainder of 3.
Record the quotient 1 as the next digit in the result. 
Result so far: 2811.0
Subtracting 15 from 18 leaves us with 3.
Grab the next digit (9) from the dividend, add it to 3, then carry on: 39 / 15

Let's proceed to step 6:
15 goes into 39 2 times with a remainder of 9.
Record the quotient 2 as the next digit in the result. 
Result so far: 28112.0
The remainder is 9 after subtracting 30 from 39.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Step 7:
90 divided by 15 is 6 with a remainder of 0.
Record the quotient 6 as the next digit in the result. 
Result so far: 28112.6
Subtract 90 from 90 to get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Moving on to step 8:
0 divided by 15 is 0 with a remainder of 0.
Record the quotient 0 as the next digit in the result. 
Result so far: 28112.6
Deduct 0 from 0 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Step 9:
When dividing 0 by 15, we get 0 with a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 28112.6
Subtracting 0 from 0 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The final outcome is 28112.6, with a leftover of 0.0.